I remembered!  I thought and thought and couldn't come up with whatever it was, so I decided to just look at it again and see what else might float to the top.  Suddenly it came to me, and it was the same thought I'd had earlier!  :D  Yay!  Brain still functioning, even if it IS in a bit of a circle.  LOL!  This is a crankshaft for a boat motor that hangs on the wall of the building I work in.  It's to let delivery people know which door to stop at. 

"If your pictures aren't good enough, you're not close enough."  ...  Robert Capa